<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>promise对象的all方法</title>
</head>
<body>
    
</body>
<script>
    //promise.all() 将多个promise的实例合并成一个新的实例
    //只有所有的promise实例的状态都为fulfilled状态,最终结果才能执行.then
    //只要有一个promise实例的状态都为rejected状态,最终结果才能执行.catch
    let promise1 = new Promise((resolve,reject)=>{
        setTimeout(()=>{
            resolve(1000)
        },1000)
    })

     let promise2 = new Promise((resolve,reject)=>{
        setTimeout(()=>{
            resolve('hello')
        },1000)
    })

     let promise3 = new Promise((resolve,reject)=>{
        setTimeout(()=>{
            resolve('promise3失败了')
        },1000)
    })

    let promise4 =Promise.all([promise1,promise2,promise3])
    .then((res)=>{
        console.log(res);
    })
    .catch((err)=>{
        console.log(err)
    })
</script>
</html>